Onishi Masayoshi, Yasunaga Teruo, Tanaka Hiromitsu, Nishimune Yoshitake, Nozaki Masami
Department of Science for Laboratory Animal Experimentation, Research Institute for Microbial Diseases, Osaka University, 3-1 Yamadaoka, Suita City, Osaka 565-0871, Japan.
Genomics. 2004 Apr;83(4):647-57. doi: 10.1016/j.ygeno.2003.09.018.
OXCT/SCOT is the rate-determining enzyme in ketolysis in mitochondria of many extrahepatic organs. Two testicular isoforms, Oxct2a and Oxct2b, are highly homologous and specifically expressed in haploid spermatids of the mouse. In this report, we analyzed the structure and evolution of Oxct2a and Oxct2b. Both Oxct2's are single-copy intronless genes, of which nucleotide sequences are conserved with Oxct, indicating that these genes are transposons generated from Oxct. A CpG island was found within both Oxct2's. Oxct2a and Oxct2b are located in the third introns of Bmp8a and Bmp8b, and they are positioned within a 240-kb region in a tail-to-tail orientation on chromosome 4. This structural feature was also conserved in a syntenic region of human 1p34.3. Structural similarity between mice and humans indicated that these two sets of genes were generated by a segmental gene duplication, which occurred before the primate-rodent split. Dot matrix and phylogenetic tree analyses demonstrated that multiple rounds of intrachromosomal gene conversion between the two loci occurred in each species independently.
OXCT/SCOT是许多肝外器官线粒体中酮体分解的限速酶。睾丸中的两种同工型，即Oxct2a和Oxct2b，高度同源，且在小鼠单倍体精子细胞中特异性表达。在本报告中，我们分析了Oxct2a和Oxct2b的结构与进化。两种Oxct2均为单拷贝无内含子基因，其核苷酸序列与Oxct保守，表明这些基因是由Oxct产生的转座子。在两种Oxct2中均发现了一个CpG岛。Oxct2a和Oxct2b位于Bmp8a和Bmp8b的第三个内含子中，它们在4号染色体上以尾对尾的方向位于一个240 kb的区域内。这种结构特征在人类1p34.3的同线性区域中也保守。小鼠和人类之间的结构相似性表明，这两组基因是由一次片段性基因复制产生的，该复制发生在灵长类-啮齿类分化之前。点阵和系统发育树分析表明，两个基因座之间的多轮染色体内基因转换在每个物种中独立发生。
